Korg XVP-20 VOL/EXP

My old Korg Expression pedal from the 80s, which made a crackling sound when operated, so I decided to buy a new Korg pedal instead of restoring the old one. Since the organ sounds of my Korg SV1 are much louder than the (E-)piano sounds, it's necessary to control the volume live. The material and construction quality of the Korg XVP-20 VOL/EXP are very high. However, despite this, I was still disappointed when using it with the Korg SV1. Instead of connecting four audio cables to the pedal, I found it more practical to connect a stereo 3.5mm jack to the expression pedal port of the Korg SV1. The pedal works, but the 'Min Volume' potentiometer seems to be ineffective. Additionally, the usable volume range with the foot pedal was between 0cm and 1-2cm of movement, after which the Korg SV1 became very quiet. It seems that the pedal's potentiometer is not linear, while the Korg SV1 is linear... I think Korg needs to improve this in the SV1 or XVP-20. It might also be that the pedal works better with a Korg Kronos. However, this doesn't fully explain why reputable German retailers offer the Korg SV1 with this expression pedal as a bundle. If I control the volume of the Korg SV1 via four audio cables, then the 'Min Volume' potentiometer works, and the volume can be dosed as expected, and the sound quality is not noticeably affected by the pedal.